doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Sticky opening gun

Jim, i beg your pardon but not all rim cutters are built into chamber reamer! i have cut a good many rims for 20 gauge shells on the new old stock Fox barrels and i have a rim cutter that is made for that purpose ,not to ream chambers.It could very well be the problem. If rims cut too deep all the way around firing pins need to be longer in order to fire the shells. Bobby

Bobby-





This is exactly what I was thinking/referring to in my mention of 'chamber work' -- your comment about the rim cutter is a good one.
Those chambers do look 'tarted up' a bit though...


But if the OP is getting things to work with a simple switch of ammunition, that may well be the route he'd want to take. Likely the cheapest way to go.



--Tinker

I'm happy to be corrected Bobby. However, surely the separate rim cutters you describe would still be intended to cut the rim recesses perpendicular to the bores, wouldn't they? If not, why not? In this gun the rims are obviously(to me, at least) cut too deep already, whether they are square with the bores or not. That's why the primers are backing out of the battery cups, as is clearly shown in the pictures.

Jim, it is really hard to tell by the pictures.My cutter is used by hand and has a guide affair with some type spring i believe. Would have to go dig it out. Anyway i have cut some rims and then checked with shell pushed in and i needed to put light pressure on the side that needed cutting slightly deeper. Some of these gunsmiths on here know much more than i .kind regards, Bobby

Looking back at the pictures, #2 pic does indeed look like the rim cut is deeper at the top than at the bottom. And by his measurements, .018" and .025" doesn't sound like the shells are setting way too deep. Another thought is that if some bozo has removed those bushings to install the new, ugly firing pins, they may have the bushings screwed in too deep, maybe even switched. This could account for the primers backing out, as they obviously have. Primer bushings usually do not screw in tight to make them flush with the breech face. They need to be in their original holes, to start with, and stopped at the witness marks. It's also not uncommon for cheap guns to have the cocking levers or rods wear so that they do not start to cock the hammers soon enough, to take the pressure off the firing pins. I'd start by shortening the firing pins(out of the gun), to get about .040-.045" protrusion. Them when reinstalling, make sure the bushings are in the right holes and screwed in just enough to make them exactly flush with the standing breech. Them, if the problem still persists, work on the cocking parts to make cocking occur sooner. Go slow on this because if you go too far, they will prevent the hammers/firing pins from going forward far enough, when firing. I went through this with a cheap Crescent .410. It also had very deep rim cuts. Lots of newer shells have thinner rims than some of the very older shells, in use when some of the older guns were made.

Just checked fp protrusion on two of my guns. An Ugartechea grade II 28 ga. protrudes .022-.025"(not an expensive gun). A 1926 Parker, both pins(integral with hammers), protrude about .040". Both guns never misfire and never stick on opening. I think .040" is plenty.

In the original pic with the pins in the gun they looked as if they had a sort of conical point to them. In the latest pic of the pins out they appear to simply be flat bottomed. I think that light reflection made them appear to come to a point in thar first pic. I would put a hemispherical radius on the ends of those pins. That flat end in the primer indent will actually tend to act as a bolt, while the rounded end will help to cam the pin back on opening.

After looking at these latest pictures, and reading your post, I think the previous molester has swapped the firing pins. The shallow dimple on the shell from the left chamber and the deep dimple on the shell from the right chamber would be cured by the longer pin being in left side and the shorter in the right. Does that make sense?

binko

After looking at these latest pictures, and reading your post, I think the previous molester has swapped the firing pins. The shallow dimple on the shell from the left chamber and the deep dimple on the shell from the right chamber would be cured by the longer pin being in left side and the shorter in the right. Does that make sense?

binko

Today while firing with snap caps and opening the gun slowly I noticed that when I had it opened enough to see between the barrels and breech face the pins were still protruding. It isn't until the barrels are 1/4" or more above the fences that the pins are no longer visible. As you might expect the right one disappears before the left one.



There have been several comments on the pins themselves. What is it about those pins (aside from the fact that are probably the culprit) that identifies them as being replacements? I will switch the bushings and pins around separately and together and see what difference that makes in pin protrusion or anything else. There are no witness marks. What might look like them in the first picture was deposits from the Winchester primers.


The longer pin fired the left barrel. Four of those are from the right barrel with the shorter pin. I don't know which one was shot in the left barrel but I do know that it was one of the Winchester hulls.